Polyline Inlet Light Guide for Uniform Automotive Lighting

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Solution Overview

Problem

Existing automotive lighting and signaling devices with LED light sources and light guides often suffer from uneven light distributions and overlapping light spots, particularly in devices with long and thin light guides, leading to non-uniform illumination.

Innovation Solution

The use of a rigid union technique for assembling internal components within a container body, combined with a light guide featuring a polyline geometry inlet wall and optical extractor elements on the rear wall, ensures uniform light distribution and prevents light spots.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a light guide has an overall reduced thickness and a particularly extensive rear wall (outcoupling), then the light guide can be made more compact and adaptable to various vehicle applications, but uneven concentrations and overlapping of light rays occur on the rear wall, creating visible spots and non-uniform illumination

Engineering Contradiction:
Improvelight guide thicknessVSAvoidlight distribution uniformity
Core Design Contradiction:
Volume of moving objectVSManufacturing precision

Solution Approach 1:

The inlet wall is designed with different geometric configurations (polyline geometry with specific angles) in different regions to locally control light ray trajectories. This ensures that light rays are distributed more uniformly across the extensive rear wall, preventing concentration and overlapping in specific areas while maintaining the reduced thickness of the light guide.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent introduces a new geometric dimension by using polyline geometry with specific angles (α and β) in the inlet wall cross-section. This dimensional approach allows control over light ray paths in three-dimensional space, enabling uniform light distribution across the extensive rear wall while keeping the light guide thickness reduced.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If separate light rays are reflected successively inside the light guide, then the light guide can channel light effectively, but the light rays tend to overlap and concentrate in inhomogeneous manner in certain areas of the outcoupling, creating spots

Engineering Contradiction:
Improvelight channeling efficiencyVSAvoidlight ray distribution uniformity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The inlet wall geometry is specifically designed with different angular sections (α and β) to locally redirect light rays from different LED sources. This local geometric control ensures that successive reflections distribute light rays more evenly across the outcoupling, preventing the formation of concentrated spots while maintaining effective light channeling.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The polyline geometry of the inlet wall uses asymmetric angles (α and β) to create non-uniform light ray paths that compensate for the natural tendency of light to concentrate. This asymmetric design ensures that light rays from multiple LED sources are distributed more uniformly across the extensive rear wall, preventing spot formation while maintaining channeling efficiency.

Inventive Principle:
Principle #4Asymmetry

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution achieves a homogeneous and uniform lighting distribution across the rear wall of the light guide, eliminating light spots and ensuring consistent illumination, even in devices with long and thin light guides.

Implementation Method 1

a light guide (24) formed with a transparent polymeric material and configured to at least partially receive the light beam generated by said light source at an inlet wall (36) of the light guide, convey the light rays and extract the light rays by means of a rear wall (40)

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

The light beam is reflected into the light guide and extracted through a front wall by means of specific extractors arranged along a rear wall

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP4286742B1Automotive lighting and/or signaling device with a light guide
Publication Date: 2025.05.14 MARELLI AUTOMOTIVE LIGHTING ITAL SPA
  • EP4286742B1 patent drawingFigure 1
  • EP4286742B1 patent drawingFigure 2
  • EP4286742B1 patent drawingFigure 3a~3b

AI summary

A lighting and/or signaling device (4) for vehicles comprising a container body (8) that delimits a containment seat (12) which extends along a first perimeter edge (28), closed by a lenticular body (20) that extends along a second perimeter edge (32) at least partially counter-shaped to and overlapping said first perimeter edge (28), said containment seat (12) housing at least one LED or mini LED light source (16) adapted to emit a light beam comprising a plurality of light rays (18) which extend along a main optical propagation axis (X-X), and at least one light guide (24) configured to at least partially receive said light rays (18) at an inlet wall (36) thereof and to transmit and/or reflect said light rays (18) onto a rear wall (40) thereof. The rear wall (40) is provided with a plurality of optical extractor elements (44) which extract the light rays (18) and transmit them externally to the light guide (24) through a front wall (48) of the light guide (24), opposite to said rear wall (40), along a transverse direction (T-T), perpendicular to the main optical propagation axis (X-X). With respect to a cross-section plane passing through said main optical propagation axis (X-X) and said transverse direction (T-T), the inlet wall (36) has a middle section (52) with polyline geometry comprising a plurality of rectilinear sections and/or curvilinear sections (56) so as to overall be convex on the side of the at least one light source (16).